US7675380B2 - Integrated digitally controlled linear-in-decibels attenuator - Google Patents

Integrated digitally controlled linear-in-decibels attenuator Download PDF

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US7675380B2
US7675380B2 US11/876,482 US87648207A US7675380B2 US 7675380 B2 US7675380 B2 US 7675380B2 US 87648207 A US87648207 A US 87648207A US 7675380 B2 US7675380 B2 US 7675380B2
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electrodes
coupled
signal
shunt
resistances
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US20090072931A1 (en
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Hon Kin Chiu
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National Semiconductor Corp
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National Semiconductor Corp
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Priority to US11/876,482 priority Critical patent/US7675380B2/en
Priority to JP2010531201A priority patent/JP2011503939A/ja
Priority to PCT/US2008/080759 priority patent/WO2009055449A1/en
Priority to TW097140412A priority patent/TW200919952A/zh
Priority to DE112008002825T priority patent/DE112008002825T5/de
Priority to CN200880123047XA priority patent/CN102007695A/zh
Publication of US20090072931A1 publication Critical patent/US20090072931A1/en
Priority to US12/719,432 priority patent/US8076995B2/en
Publication of US7675380B2 publication Critical patent/US7675380B2/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/24—Frequency- independent attenuators

Definitions

  • the present invention relates to signal attenuation circuits, and in particular, to digitally controlled signal attenuation circuits.
  • Digitally controlled attenuator circuits are well-known in the art. Such attenuator circuits are generally used in controlled impedance environments, and allow the attenuation to be controlled in units or fractions of decibels (dB).
  • dB decibels
  • One particular type of such attenuator is referred to as a linear-in-dB attenuator, in which a thermometer code type of switching, or control, signal causes the attenuation to vary in single dB steps.
  • a conventional digitally controlled linear-in-dB attenuator includes a resistive ladder circuit with series resistances Rs 2 -Rs 7 and shunt resistances Rp 1 -Rp 7 , interconnected substantially as shown, to which the input voltage signal Vin is applied.
  • the voltages at nodes N 1 -N 7 are applied to the throw electrodes of the single-pole, single-throw switch circuits S 1 -S 7 .
  • the pole electrodes of these switches S 1 -S 7 are mutually connected to provide the output signal Vout.
  • the switches S 1 -S 7 are controlled with a thermometer code control signal to selectively close the individual switches, depending upon the desired attenuation.
  • the series resistances Rs 2 -Rs 7 would have nominal resistance values of 109 ohms, while the shunt resistances Rp 1 -Rp 7 would have nominal resistances of 8170 ohms.
  • a problem with such conventional attenuator circuits is the limited bandwidth caused by the circuit topology.
  • the attenuation is no longer constant and begins to increase.
  • the switch circuits S 1 -S 7 which are typically implemented using metal oxide semiconductor field effect transistor (MOSFET) switches with low turn-on resistances.
  • MOSFET metal oxide semiconductor field effect transistor
  • such devices typically have relatively high parasitic capacitances at their drain and source electrodes. It is this parasitic capacitance that causes the bandwidth to be limited, thereby causing the attenuation characteristics to no longer be constant above a certain frequency Fc.
  • the bandwidth decreases as the attenuation increases. This is caused by the increased capacitance due to more of the switches S 1 -S 7 being in their off states.
  • An integrated digitally controlled linear-in-decibels attenuator circuit in which one or more sets of selection switches establish a desired attenuation by selectively connecting the input signal electrode to one or more corresponding resistive ladder networks connected in series, thereby providing a substantially more constant signal attenuation value over a wider frequency bandwidth.
  • attenuation control is achieved using a thermometer switching code.
  • coarse and fine attenuation control can be achieved using thermometer and bubble switching codes, respectively.
  • an integrated digitally controlled linear-in-decibels attenuator circuit includes:
  • thermometer code a plurality of attenuation control electrodes to convey a plurality of digital control signals corresponding to a signal attenuation value in accordance with a thermometer code
  • an output signal electrode to convey an output signal corresponding to the input signal and having a magnitude which is less than the input signal magnitude in relation to the signal attenuation value
  • a resistive network coupled between the input and output signal electrodes and responsive to the plurality of digital control signals by attenuating the input signal to provide the output signal.
  • an integrated digitally controlled linear-in-decibels attenuator circuit includes:
  • thermometer code a first plurality of attenuation control electrodes to convey a first plurality of digital control signals corresponding to a first signal attenuation value in accordance with a thermometer code
  • a second plurality of attenuation control electrodes to convey a second plurality of digital control signals corresponding to a second signal attenuation value in accordance with a bubble code
  • an intermediate signal electrode to convey an intermediate signal corresponding to the input signal and having a magnitude which is less than the input signal magnitude in relation to the first signal attenuation value
  • an output signal electrode to convey an output signal corresponding to the intermediate signal and having a magnitude which is less than the intermediate signal magnitude in relation to the second signal attenuation value
  • a first resistive ladder network coupled between the input and intermediate signal electrodes and responsive to the first plurality of digital control signals by attenuating the input signal to provide the intermediate signal
  • a second resistive ladder network coupled between the intermediate and output signal electrodes and responsive to the second plurality of digital control signals by attenuating the intermediate signal to provide the output signal.
  • FIG. 1 is a schematic diagram of a conventional digitally controlled linear-in-dB attenuator circuit.
  • FIG. 1A is a graph of attenuation versus frequency for the circuit of FIG. 1 .
  • FIG. 2 is a schematic diagram of a digitally controlled linear-in-dB attenuator circuit in accordance with one embodiment of the presently claimed invention.
  • FIG. 2A is a graph of attenuation versus frequency for the circuit of FIG. 2 .
  • FIG. 3 is a schematic diagram of one example of an implementation of a switch circuit for the attenuator circuit of FIG. 2 .
  • FIG. 4 is a block diagram of a digitally controlled linear-in-dB attenuator circuit in accordance with another embodiment of the presently claimed invention.
  • FIG. 5 is a table of thermometer and bubble codes for attenuator control signals in accordance with one embodiment of the presently claimed invention.
  • FIG. 6 is a graph of attenuation levels versus time for the attenuator circuit of FIG. 4 with the attenuator control signals of FIG. 5 .
  • signal may refer to one or more currents, one or more voltages, or a data signal.
  • an integrated digitally controlled linear-in-dB attenuator circuit in accordance with one embodiment of the presently claimed invention includes a resistive ladder circuit, with series resistances Rs 2 -Rs 7 and shunt resistances Rp 1 -Rp 7 , and single-pole, double-throw switch circuits S 1 -S 6 , all interconnected substantially as shown.
  • the input signal Vin is applied to the series resistances Rs 2 -Rs 7 via resistance Rp 7 , and to resistances Rp 1 -Rp 6 via the switch circuits S 1 -S 6 . Accordingly, the output signal Vout is provided at the output of the resistive ladder circuit (e.g., as opposed to the mutually connected pole electrodes of the switch circuits S 1 -S 6 ).
  • this circuit topology advantageously maintains a sufficient output impedance at the output node No since the pole electrodes of the switch circuits S 1 -S 6 are isolated from the output node No by the shunt Rp 1 -Rp 6 and series Rs 2 -Rs 6 resistances, and the throw electrodes are connected either to the low impedance input node Ni or to low impedance circuit ground GND, depending upon the desired signal attenuation.
  • the signal attenuation remains more constant over a wider frequency bandwidth due to the isolation of the parasitic capacitances of the switch circuits S 1 -S 6 from the output node No.
  • an example embodiment of a switch circuit e.g., the first switch circuit S 1 , includes pairs of N-type and P-type MOSFETs interconnected as transmission gates.
  • complementary pairs N 1 , P 1 and N 2 , P 2 of MOS transistors are interconnected with mutually coupled drain and source electrodes as shown.
  • the incoming control signal drives the gate electrodes of transistors N 1 and P 2
  • the inverted control signal inverted by an inverter circuit INV
  • the control signal is asserted high, the N 1 -P 1 transistor pair is turned on while the N 2 -P 2 transistor pair is turned off.
  • transistor pair N 2 -P 2 is turned on while transistor pair N 1 -P 1 is turned off.
  • single transistors can be used as pass transistors.
  • transistors N 1 and P 2 can be used with transistors P 1 and N 2 omitted.
  • a digitally controlled linear-in-dB attenuator circuit 400 in accordance with another embodiment of the presently claimed invention includes at least two stages 200 , 100 connected in series, with the first stage 200 being a circuit in conformance with FIG. 2 , and the second stage 100 being a circuit in conformance with FIG. 1 (with the output node No of FIG. 2 connected to the input node N 7 of FIG. 1 ). Accordingly, with the two stages 200 , 100 implemented as the example circuits of FIGS.
  • preferred relative values of the resistances in the first stage 200 (Rs 2 -Rs 7 and Rp 1 -Rp 7 ) and second stage 100 (Rs 2 -Rs 7 and Rp 1 -Rp 7 ) are as follows (where a ⁇ 1 and k ⁇ 1):
  • the attenuator control signals i.e., the switch control signals CONTROL ( FIGS. 1 and 2 )
  • the first stage 200 provides coarse attenuation control in accordance with thermometer code
  • the second stage 100 provides fine attenuation control in accordance with bubble code.
  • thermometer code for such a R-2R resistive ladder network is the ability to provide linear-in-dB attenuation. This is in contrast to the use of binary code which would provide linear-in-voltage control.
  • Attenuation levels versus time are shown for the attenuator circuit of FIG. 4 using the thermometer and bubble codes of FIG. 5 for the attenuator control signals.

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  • Attenuators (AREA)
  • Networks Using Active Elements (AREA)
  • Control Of Amplification And Gain Control (AREA)
US11/876,482 2005-06-14 2007-10-22 Integrated digitally controlled linear-in-decibels attenuator Active US7675380B2 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US11/876,482 US7675380B2 (en) 2005-06-14 2007-10-22 Integrated digitally controlled linear-in-decibels attenuator
DE112008002825T DE112008002825T5 (de) 2007-10-22 2008-10-22 Integrierter, digital gesteuerter Dezibel-linearer Dämpfungsschaltkreis
PCT/US2008/080759 WO2009055449A1 (en) 2007-10-22 2008-10-22 Integrated digitally controlled linear-in-decibels attenuator
TW097140412A TW200919952A (en) 2007-10-22 2008-10-22 Integrated digitally controlled linear-in-decibels attenuator
JP2010531201A JP2011503939A (ja) 2007-10-22 2008-10-22 集積化デジタル制御型ｄＢ直線性アッテネータ
CN200880123047XA CN102007695A (zh) 2007-10-22 2008-10-22 整合式数字控制的以分贝为单位的线性衰减器
US12/719,432 US8076995B2 (en) 2005-06-14 2010-03-08 Integrated digitally controlled linear-in-decibels attenuator

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US16021005A 2005-06-14 2005-06-14
US50002406A 2006-08-07 2006-08-07
US11/876,482 US7675380B2 (en) 2005-06-14 2007-10-22 Integrated digitally controlled linear-in-decibels attenuator

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US50002406A Continuation-In-Part 2005-06-14 2006-08-07

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US12/719,432 Continuation US8076995B2 (en) 2005-06-14 2010-03-08 Integrated digitally controlled linear-in-decibels attenuator

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US12/719,432 Active 2025-09-29 US8076995B2 (en) 2005-06-14 2010-03-08 Integrated digitally controlled linear-in-decibels attenuator

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JP (1) JP2011503939A (zh)
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WO (1) WO2009055449A1 (zh)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090149743A1 (en) * 2005-11-21 2009-06-11 Acist Medical Systems, Inc. Medical Fluid Injection System
US20110156942A1 (en) * 2009-12-31 2011-06-30 Qunying Li Reduced area digital-to-analog converter
US9356577B2 (en) * 2014-08-12 2016-05-31 Freescale Semiconductor, Inc. Memory interface receivers having pulsed control of input signal attenuation networks
US10291207B2 (en) 2016-07-07 2019-05-14 Analog Devices, Inc. Wide range programmable resistor for discrete logarithmic control, and tuning circuit for variable gain active filter using same
US20230283268A1 (en) * 2022-03-01 2023-09-07 Qualcomm Incorporated Current-mode radio frequency attenuators

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Publication number Priority date Publication date Assignee Title
US7911293B2 (en) * 2009-06-26 2011-03-22 Bae Systems Information And Electronic Systems Integration Inc. Thermometer coded attenuator
US9100046B2 (en) * 2011-08-17 2015-08-04 Rf Micro Devices, Inc. Digital step attenuator utilizing thermometer encoded multi-bit attenuator stages
US9473109B2 (en) 2014-05-09 2016-10-18 Skyworks Solutions, Inc. Apparatus and methods for digital step attenuators with small output glitch
US9584096B2 (en) 2014-05-09 2017-02-28 Skyworks Solutions, Inc. Apparatus and methods for digital step attenuators with low phase shift
US10082488B2 (en) 2015-12-02 2018-09-25 Butterfly Network, Inc. Time gain compensation circuit and related apparatus and methods
US10498383B2 (en) 2016-02-26 2019-12-03 Skyworks Solutions, Inc. Attenuation circuits with low insertion loss, and modules and devices using same
WO2018035178A1 (en) 2016-08-16 2018-02-22 Skyworks Solutions, Inc. Digital switched attenuator
US10231713B2 (en) 2016-09-13 2019-03-19 Butterfly Network, Inc. Analog-to-digital drive circuitry having built-in time gain compensation functionality for ultrasound applications
US10396735B2 (en) 2016-11-11 2019-08-27 Skyworks Solutions, Inc. Amplifier system with digital switched attenuator
US10505511B1 (en) 2018-06-20 2019-12-10 Psemi Corporation High resolution attenuator or phase shifter with weighted bits

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090149743A1 (en) * 2005-11-21 2009-06-11 Acist Medical Systems, Inc. Medical Fluid Injection System
US9259526B2 (en) 2005-11-21 2016-02-16 Acist Medical Systems, Inc. Medical fluid injection system and method for guided setup
US10226568B2 (en) 2005-11-21 2019-03-12 Acist Medical Systems, Inc. Customizable medical fluid injection system and method
US20110156942A1 (en) * 2009-12-31 2011-06-30 Qunying Li Reduced area digital-to-analog converter
US8013772B2 (en) * 2009-12-31 2011-09-06 Texas Instruments Incorporated Reduced area digital-to-analog converter
US9356577B2 (en) * 2014-08-12 2016-05-31 Freescale Semiconductor, Inc. Memory interface receivers having pulsed control of input signal attenuation networks
US10291207B2 (en) 2016-07-07 2019-05-14 Analog Devices, Inc. Wide range programmable resistor for discrete logarithmic control, and tuning circuit for variable gain active filter using same
US20230283268A1 (en) * 2022-03-01 2023-09-07 Qualcomm Incorporated Current-mode radio frequency attenuators

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US20090072931A1 (en) 2009-03-19
DE112008002825T5 (de) 2011-02-03
WO2009055449A1 (en) 2009-04-30
TW200919952A (en) 2009-05-01
CN102007695A (zh) 2011-04-06
JP2011503939A (ja) 2011-01-27
US20100164656A1 (en) 2010-07-01
US8076995B2 (en) 2011-12-13

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